Default Type Conversion

When two numeric expressions are combined, the data types of the expressions are converted to be identical; this conversion determines the data type of the result. The expression having the data type of lower precedence is converted to the data type of higher precedence.

For example, in an operation that combines an integer and a floating point number, the integer is converted to a floating point number before the operation is performed. If the operands are two integers of different sizes, the smaller is converted to the size of the larger.

the first operator (+) combines a float4 expression (job.lowsal) with a smallint constant (1000). The result is float4. The second operator (*) combines the float4 expression with a smallint constant (12), resulting in a float4 expression.

	integer1	integer2	integer4	integer8	decimal*	float8	float4	money
integer1	integer8	integer8	integer8	integer8	decimal6	float8	float4	money
integer2	integer8	integer8	integer8	integer8	decimal6	float8	float4	money
integer4	integer8	integer8	integer8	integer8	decimal12	float8	float4	money
integer8	integer8	integer8	integer8	integer8	decimal20	float8	float4	money
decimal*	decimal6	decimal6	decimal12	decimal20	decimal6	float8	float4	money
float8	float8	float8	float8	float8	float8	float8	float4	money
float4	float4	float4	float4	float4	float4	float4	float4	money
money	money	money	money	money	money	money	money	money
	*decimal(n) – The result size depends on the size of the decimal. The result size shown is for adding decimal(1) to the other value, for example: decimal(1) + int2(1).